Government and private sector organizations need to collect large amounts of detailed information from a variety of individuals, on a variety of topics, in a variety of settings, for a variety of reasons, in a timely and cost-effective manner. These last two constraints have spurred the development or adaptation of computer-assisted measurement technologies. Implicit to this massive data collection and consumption is its accuracy (reliability): inaccurate data have zero, or negative, utility. However, most organizations, including research organizations, underestimate the cost of "good" data, substituting face-valid assumptions about its collection for more rigorous procedures. The Phase I objectives of this proposal are to systematically explore and delineate those factors which assist or hinder acquisition of data of varying sensitivity from substance abusing individuals, identify potential solutions and strategies to overcome obstacles, to develop an affordable computer-assisted self- interview (CASI) of substance usage, and to evaluate the quality of the data collected by this prototype (in terms of reliability and criterion validity) with that collected by a more traditional method - a face-to- face interview - among relatively low functioning individuals.